TABLE 4

Antibiotic Use and Laboratory Testing

Pre-SRC (n = 5692)Post-SRC (n = 6090)Relative Risk (95% CI)
Antibiotics ≤72 h, n (%)356 (6.3)222 (3.7)0.58 (0.50–0.69)
Antibiotics <7 d, n (%)361 (6.3)224 (3.7)0.58 (0.49–0.68)
Laboratory testing: all infants born ≥36 wk
 Any EOS laboratory testing, n (%)a1529 (26.9)299 (4.9)0.18 (0.16–0.21)
  Blood culture and CBC/diff and CRP testing, n (%)372 (6.5)95 (1.6)0.24 (0.19–0.30)
  Blood culture and CBC/diff, n (%)26 (0.5)69 (1.1)2.50 (1.58–3.90)
  Blood culture only, n (%)39 (0.7)97 (1.6)2.33 (1.61–3.37)
  CBC/diff and CRP testing, n (%)1087 (19.1)35 (0.6)0.03 (0.02–0.04)
  CBC only, n (%)135 (2.4)140 (2.3)0.97 (0.76–1.22)b
Laboratory testing: NICU admissions onlyPre-SRC (n = 719)Post-SRC (n = 732)
 Any EOS evaluation, n (%)c562 (78.2)291 (39.8)0.51 (0.46–0.56)
  Blood culture and CBC/diff and CRP testing, n (%)372 (51.7)95 (13.0)0.25 (0.21–0.31)
  Blood culture and CBC/diff, n (%)26 (3.6)69 (9.4)2.61 (1.68–4.04)
  Blood culture only, n (%)39 (5.4)97 (13.3)2.44 (1.71–3.49)
  CBC/diff and CRP testing, n (%)125 (17.4)27 (3.7)0.21 (0.14–0.32)
CBC count only, n (%)63 (8.8)90 (12.3)1.40 (1.03–1.90)d
  • Any EOS evaluation includes any combination of blood culture, CBC count with white blood cell differential, and/or CRP testing, excluding the CBC count in isolation. Relative risk is that of the procedure occurring in the post-SRC period compared with the pre-SRC period. All differences except for CBC count alone have P < .001. CBC/diff, complete blood cell count with white blood cell differential measurement.

  • a Five infants in the pre-SRC period had a CRP only, and 3 infants in the post-SRC period had a blood culture and CRP testing (CBC count clotted in each case and was not repeated in 72 h).

  • b P = .84.

  • c Three infants in the post-SRC had a blood culture and CRP testing.

  • d P = .03.